CN114033350A - Methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system and method - Google Patents
Methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system and method Download PDFInfo
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- CN114033350A CN114033350A CN202111359137.2A CN202111359137A CN114033350A CN 114033350 A CN114033350 A CN 114033350A CN 202111359137 A CN202111359137 A CN 202111359137A CN 114033350 A CN114033350 A CN 114033350A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/14—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor using liquids and gases, e.g. foams
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
- E21B43/121—Lifting well fluids
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/164—Injecting CO2 or carbonated water
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/263—Methods for stimulating production by forming crevices or fractures using explosives
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B35/00—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
- F04B35/04—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric
- F04B35/045—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric using solenoids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
- F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
- F04B37/18—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use for specific elastic fluids
Abstract
The invention discloses a methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system and method, which are suitable for extraction of a natural gas reservoir with ultra-low permeability. Vertically drilling a working well with a step structure into a natural gas reservoir, and then directionally drilling a plurality of gas injection wells and a plurality of exhaust wells on two sides of the working well; feeding a sieve tube to the area below the step of the working well in advance, and installing a temperature-resistant wear-resistant sleeve above the step; a working piston is arranged in the temperature-resistant and wear-resistant sleeve, and a signal transceiver is arranged at a wellhead; the temperature-resistant and wear-resistant sleeve controls the working piston to move up and down through magnetic force so as to compress gas in the working well; igniting and exciting methane for combustion and explosion; and acquiring height information of the working piston pushed by the burning explosion, and starting an exhaust well for extraction when the working piston reaches the maximum. The method has the advantages of effectively fracturing the natural gas reservoir, strengthening the stability of the seepage channel, along with simple operation, and being beneficial to control and automatic circulation.
Description
Technical Field
The invention relates to a circulating natural gas enhanced extraction system and a circulating natural gas enhanced extraction method, in particular to a methane in-situ combustion-explosion fracturing circulating natural gas enhanced extraction system and a methane in-situ combustion-explosion fracturing circulating natural gas enhanced extraction method which are suitable for extraction of ultra-low permeability natural gas reservoirs.
Background
The unconventional natural gas reservoir in China is an ultra-low permeability natural gas layer generally and belongs to the range of Nadarcy seepage. The gas-containing shale is in an ultra-sealed state and is regarded as zero permeability, and methane is not easy to desorb and diffuse. At present, the common mainstream natural gas reservoir transformation methods comprise a hydraulic fracturing method, a perforation combined method and a pulse blasting method. The hydraulic fracturing method has low discharge capacity and poor time benefit, and the fracturing fluid is easy to pollute the surrounding water body by being doped with various chemical substances; the perforation combination method can control the position of the crack with accurate control and cannot be used for unstable boreholes; the pulse blasting method uses solid or liquid explosive to initiate shock waves to destroy natural gas reservoirs, the blasting action range is limited, and blasting residues easily block cracks.
Disclosure of Invention
The invention aims to provide a circulating natural gas enhanced extraction system and method for methane in-situ combustion-explosion fracturing, which are used for solving the problems in the prior art, have simple operation process, strong methane in-situ combustion-explosion impact and obvious anti-reflection effect and can perform circulating combustion-explosion fracturing.
In order to achieve the purpose, the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system comprises a working well drilled into a natural gas reservoir, wherein the working well is a stepped well with a thick upper end and a thin lower end, a well section with the thick upper end is a piston well section, and a fracturing well section is washed at the lower end; the device comprises a piston well section, a fracturing well section, a screen pipe, a well mouth, a movable clamp, a plurality of gas injection wells and a plurality of gas exhaust wells, wherein a joint of the piston well section and the fracturing well section is a step, a rubber ring for sealing is arranged on the step, the fracturing well section below the rubber ring is internally provided with the screen pipe, the screen pipe is fully distributed with a plurality of round holes, the piston well section is internally provided with a temperature-resistant and wear-resistant sleeve pipe, the tail part of the temperature-resistant and wear-resistant sleeve pipe extends out of the well mouth of a working well, the outer side of the temperature-resistant and wear-resistant sleeve pipe is tightly wound with a coil, the coil is connected with a power supply, the temperature-resistant and wear-resistant sleeve pipe is internally provided with a working piston with matched size, a well mouth signal transceiver is vertically arranged above a pipe orifice of the temperature-resistant and wear-resistant sleeve pipe through a support, the top of the temperature-resistant and wear-resistant sleeve pipe is internally provided with a movable clamp for fixing the working piston, the two sides of the working well are respectively provided with a plurality of gas injection wells and a plurality of gas exhaust wells at equal intervals, the gas injection wells are connected with the side walls above the fracturing well section through a horizontal well section; the working piston comprises an upper part and a lower part which are hinged through bolts, the upper part comprises a permanent magnet, the outer side of the permanent magnet is wrapped by a temperature-resistant wear-resistant shell, the lower part comprises a counterweight body, the top of the upper part and the bottom of the lower part are respectively provided with a polyurea coating, the circular polyurea coating arranged at the bottom of the lower part is provided with an igniter, and the top of the upper part is respectively provided with a height gauge and a working piston signal transceiver.
A plurality of gas injection wells and a plurality of gas discharge well are in equidistant relative setting in working well both sides, gas injection well and gas discharge well parallel arrangement, and two sets of well parallel spacing 20 ~ 30m, with the adjacent two wells interval 10 ~ 15m of group, the working well is arranged centrally.
The horizontal well section of the gas injection well exhaust well comprises a first valve and a second valve respectively, wherein the first valve is arranged at the position, close to the sieve tube, of the horizontal well section, the second valve is provided with a dustproof filter screen, and a methane concentration probe and an oxygen concentration probe are fixed in the horizontal well section by utilizing the second valve; and a third valve is arranged in the end part of the horizontal well section of the exhaust well, which is close to the sieve tube.
A circulating natural gas enhanced extraction method based on methane in-situ combustion explosion fracturing comprises the following steps:
a, vertically drilling a working well from a natural gas reservoir, forming a step at a position of the working well, which is 5-10 meters away from the natural gas reservoir, through a diameter difference to divide the working well into an upper piston well section and a lower fracturing well section, then directionally drilling a plurality of gas injection wells and a plurality of gas exhaust wells on the earth surface of two sides of the working well, and cleaning the gas injection wells and the gas exhaust wells by using oxygen-containing gas flow;
b, feeding a screen pipe into a fracturing well of the working well, then placing a rubber ring in the step area, installing a temperature-resistant and wear-resistant sleeve pipe wound with a coil above the rubber ring, and connecting the coil into a power supply;
c, a working piston is arranged in the temperature-resistant and wear-resistant sleeve, and a signal transceiver is vertically arranged above the wellhead of the working well by utilizing a vertical frame;
d, placing a flexible steel pipe provided with a first valve, a second valve, a dustproof filter screen, a methane concentration probe and an oxygen concentration probe in the gas injection well, and placing a flexible steel pipe provided with a third valve in the exhaust well;
e, closing the first valve and the second valve in all the gas injection wells, closing the third valve in all the gas exhaust wells, and enabling the working piston to fall to the step area from the wellhead of the working well by utilizing the magnetic force generated by electrifying the coil so as to compress the residual oxygen-containing gas and the seeped methane-containing gas in the working well;
f, enabling the working piston to repeatedly work in the temperature-resistant and wear-resistant sleeve by utilizing magnetic force generated by electrifying the coil, so as to improve the internal energy of methane gas in the working well, controlling an igniter on the working piston to ignite and excite the methane-containing gas repeatedly compressed in the sieve tube by utilizing a computer when the methane concentration is detected to reach a preset range by utilizing a methane concentration probe, so as to generate explosion, and enabling detonation gas and explosion shock waves to generate radial cracks and annular cracks through holes on the sieve tube, so that the working well is communicated with the gas injection well and the exhaust well through the radial cracks and the annular cracks;
the computer receives height information of the working piston in the sleeve pipe in real time through the wellhead signal transceiver, the height information is sent by the working piston signal transceiver, and when the height of the working piston is in a descending trend, a third valve in the flexible pipe of the exhaust well is opened to extract methane in the working well;
h after the working piston returns to the step area, the computer controls to open the first valves of all the gas injection wells, the methane concentration probe and the oxygen concentration probe which are arranged in the gas injection well are used for monitoring the natural gas yield change and the methane concentration in the working well after the explosion in real time, and the oxygen/methane concentration ratio is not more than 6: 1; when the yield of the natural gas is reduced and the methane concentration falls below 15%, a coil is electrified to generate a magnetic field to push a working piston to return to a wellhead, then a movable clamp is used for fixing and then the power is cut off, and oxygen-containing clean gas is continuously introduced through a gas injection well until the methane concentration approaches 5%;
i, repeating the steps e-h in the natural gas reservoir area, and arranging a plurality of groups of working wells at intervals, so that the circular operation of burning explosion fracturing and methane gas extraction of the methane gas reservoir can be realized, and the permeability of the methane gas reservoir is greatly improved; and controlling the ignition time of the plurality of groups of working wells to form time difference, thereby generating energy-gathered pulse waves to maximize the mechanical damage to the working wells.
And after drilling, the working well, the gas injection well and the exhaust well are cleaned of residual broken stones by using slurry pumped by a circulating pump, then the working well, the gas injection well and the exhaust well are cleaned and dried by using oxygen-containing airflow, and a drilling orifice is built and reinforced by using cement paste.
The coil is formed by combining a plurality of coil sections in parallel, and a single coil section is wound in a multilayer mode.
The diameter of the fracturing well section drilling hole of the step is 1/2 of the diameter of the piston well section.
The gas pressure of the gas injection well is controlled to be 5-10 MPa, and the oxygen concentration of pumped gas is 10%; the preset methane concentration of the blasting is 5-15%.
The thickness of the sieve tube is 10mm, and dense holes are drilled on the tube wall.
The depth of the horizontal section of the gas injection well is larger than that of the horizontal section of the exhaust well, and the vertical distance between the horizontal sections of the gas injection well and the exhaust well is 20-40 m.
Has the advantages that:
the method comprises the steps that shock waves generated by burning and exploding methane and oxygen mixed gas comprise a pressure phase and a tension phase, wherein the pressure phase generates an extrusion effect, and the tension phase generates a stretching effect, so that surrounding rock mass is mechanically damaged and fractured, and thus, a primary fracture is expanded and a new fracture is developed; the ignition of each blasting working well has time difference, so that continuous pulse waves are generated to cause each working well to be mechanically damaged in different degrees and strengthen crack development; controlling the valve of the gas injection well to open and close to produce pressure difference to continuously inject oxygen and discharge blasting gas products in time so as to realize circulating blasting fracturing; the combustion and explosion gas product contains a large amount of carbon dioxide, and displacement and methane desorption promotion are carried out, and the carbon dioxide is fixed on the shale matrix, so that carbon emission is reduced. In addition, the magnetic force pushing piston is simple in structure, the magnetic force pushing can enable the piston to move up and down to repeatedly compress, the piston is easy to install without mechanical connecting rod configuration, meanwhile, the influence of a mechanical structure is effectively avoided when the height of the working piston rising in the sleeve is detected through deflagration, the detection precision is guaranteed, meanwhile, the length of the sleeve can be combined and disassembled as required, so that the cover surface is quick in length, the working piston can also be well adapted to corresponding changes, any mechanical improvement is not needed, and the recycling and wide adaptability of the system are facilitated. The method has the advantages of effectively fracturing the natural gas reservoir, strengthening the stability of the seepage channel, along with simple operation, and being beneficial to control and automatic circulation.
Drawings
FIG. 1 is a schematic structural diagram of a burning explosion fracturing system of the methane in-situ burning explosion fracturing circulating type natural gas enhanced extraction system;
FIG. 2 is a schematic structural diagram of a working piston of the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system combustion-explosion fracturing system;
FIG. 3 is a schematic diagram of an exhaust well structure of the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system combustion-explosion fracturing system;
FIG. 4 is a schematic diagram of a coil structure of the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system combustion-explosion fracturing system;
FIG. 5 is a schematic diagram of arrangement of wells on the ground in the combustion, explosion and fracturing method of the methane in-situ combustion, explosion and fracturing circulating natural gas enhanced extraction system.
In the figure: 1-step, 2-coil, 3-working piston, 4-sleeve, 5-sieve tube, 6-exhaust well, 7-gas injection well, 8-working well, 9-rubber ring, 10-working well wellhead signal transceiver, 11-computer, 12-first valve, 13-second valve, 14-dustproof filter screen, 15-methane concentration probe, 16-oxygen concentration probe, 17-active card, 18-third valve, 301-permanent magnet, 302-temperature-resistant wear-resistant shell, 303-polyurea coating, 304-igniter, 305-altimeter and 306-working piston signal transceiver.
Detailed Description
The technical solution in the embodiment of the present invention will be described below with reference to the drawings in the embodiment of the present invention.
As shown in fig. 1, 2 and 3, the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system combustion-explosion fracturing system comprises a working well 8 drilled into a natural gas reservoir, wherein the working well 8 is a stepped well with a thick upper end and a thin lower end, a well section with a thick upper end is a piston well section, and a fracturing well section is washed at the lower end; wherein the joint of the piston well section and the fracturing well section is a step 1, a rubber ring 9 for sealing is arranged on the step 1, a sieve tube 5 is arranged in the fracturing well section below the rubber ring 9, a plurality of round holes are distributed on the sieve tube 5, a temperature-resistant and wear-resistant sleeve 4 with the tail part extending out of a working well 8 well mouth is arranged in the piston well section, a coil 2 is tightly wound outside the temperature-resistant and wear-resistant sleeve 4, the coil 2 is connected with a power supply, a working piston 3 with matched size is arranged in the temperature-resistant and wear-resistant sleeve 4, a well mouth signal transceiver 13 is vertically arranged above the pipe mouth of the temperature-resistant and wear-resistant sleeve 4 through a bracket, a movable clamp 17 for fixing the working piston 3 is arranged in the top of the temperature-resistant and wear-resistant sleeve 4, a plurality of gas injection wells 6 and a plurality of exhaust wells 7 are respectively arranged at equal intervals on two sides of the working well 8, wherein the gas injection well 6 is connected with the side wall at the bottom of the fracturing well section through a horizontal well section, and the gas exhaust well 7 is connected with the side wall above the fracturing well section through the horizontal well section; working piston 3 includes through two parts about the bolt is articulated, and upper portion includes permanent magnet 301, and permanent magnet 301 outside parcel has temperature resistant wear-resisting shell 302, and the lower part is the counterweight, and upper portion top and lower part bottom are equipped with polyurea coating 303 respectively, and wherein the circular play of polyurea coating 303 that lower part bottom set up is equipped with some firearm 304, and the upper portion top is equipped with altimeter 305 and working piston signal transceiver 306 respectively.
A plurality of gas injection wells 6 and a plurality of gas discharge well 7 are in 8 both sides equidistant relative settings of working well, and gas injection well 6 and gas discharge well 7 parallel arrangement, two sets of well parallel spacing 20 ~ 30m, with two adjacent wells interval 10 ~ 15m of group, working well 8 central arrangement.
The horizontal well section of the gas injection well 6 and the gas exhaust well 7 respectively comprises a first valve 12 and a second valve 13, wherein the first valve 12 is arranged at the position, close to the sieve tube 5, of the horizontal well section, the second valve 13 is provided with a dustproof filter screen 14, and a methane concentration probe 15 and an oxygen concentration probe 16 are fixed in the horizontal well section through the second valve 13; the end of the horizontal well section of the exhaust well 7 close to the screen pipe 5 is provided with a third valve 18.
Specifically, a working well 8 drilled into a shale area is a stepped drilling hole with a thick upper part and a thin lower part, a matched rubber ring 9 is arranged at the transition position of the stepped drilling hole, a thin drilling section below the rubber ring 9 is internally provided with a temperature-resistant and wear-resistant casing 4 with a tail part extending out of a well mouth is arranged in the thick drilling section above the rubber ring 9, the outer wall of the temperature-resistant and wear-resistant casing 4 is tightly wound with a coil 2, the coil 2 is connected with a power supply, a working piston 3 with matched size is arranged in the temperature-resistant and wear-resistant casing 4, a well mouth signal transceiver 10 is vertically arranged above the temperature-resistant and wear-resistant casing 4 through a support, a plurality of gas injection wells 6 and a plurality of gas exhaust wells 7 are respectively arranged at equal intervals on two sides of the working well 8, and the horizontal sections of the gas injection wells 6 and the gas exhaust wells 7 extend towards the working well 8;
working piston 3 includes that upper and lower two parts pass through the bolt and articulate closely and link to each other, and equal dustcoat temperature resistant wear-resisting shell 302, the size and the temperature resistant wear-resisting sleeve pipe internal diameter size of temperature resistant wear-resisting shell match, and working piston top and bottom cover one deck polyurea coating 303 respectively, and permanent magnet 301 is built-in to working piston upper half, and the top is equipped with altimeter 305 and signal transceiver 306 respectively, and working piston the latter half bottom is equipped with some firearm 304.
As shown in fig. 1, fig. 3 and fig. 5, the methane in-situ combustion-explosion fracturing circulating natural gas enhanced extraction method of the invention comprises the following steps:
a, vertically drilling a working well 8 from a natural gas reservoir, forming a step 1 at a position 5-10 meters away from the natural gas reservoir from the working well 8 through a diameter difference, dividing the working well 8 into an upper piston well section and a lower fracturing well section, as shown in figure 5, directionally drilling a plurality of gas injection wells 6 and a plurality of gas exhaust wells 7 on the earth surface at two sides of the working well 8, and cleaning the gas injection wells 6 and the gas exhaust wells 7 by using oxygen-containing gas flow; after drilling, the working well 8, the gas injection well 6 and the exhaust well 7 need to be cleaned of residual broken stones in each well by using slurry pumped circularly, then the working well 8, the gas injection well 6 and the exhaust well 7 are cleaned and dried by using oxygen-containing airflow, and a drilling orifice is built and reinforced by using cement paste; the fracturing well section drilling diameter of the step 1 is 1/2 of the diameter of the piston well section; the depth of the horizontal section of the gas injection well 6 is larger than that of the horizontal section of the exhaust well 7, and the vertical distance between the horizontal sections is 20-40 m;
b, feeding a screen pipe 5 into a fracturing well of a working well 8, then placing a rubber ring 9 in the step area 1, installing a temperature-resistant and wear-resistant sleeve 4 wound with a coil 2 above the rubber ring 9, and connecting the coil 2 into a power supply; as shown in fig. 4, the coil 2 is formed by combining a plurality of coil sections in parallel, a single coil section is wound in a multilayer mode, the thickness of the screen pipe 5 is 10mm, and dense holes are drilled on the pipe wall;
c, a working piston 3 is arranged in the temperature-resistant wear-resistant casing 4, and a signal transceiver 10 is vertically arranged above a wellhead of a working well 8 by utilizing a vertical frame;
d, placing a flexible steel pipe provided with a first valve 12, a second valve 13, a dustproof filter screen 14, a methane concentration probe 15 and an oxygen concentration probe 16 into the gas injection well 6, and placing a flexible steel pipe provided with a third valve 18 into the exhaust well 7; the pumping pressure of the gas injection well 6 is controlled to be 5-10 MPa, and the oxygen concentration of pumped gas is 10%; the preset methane concentration of the blasting is 5-15%;
e, closing the first valve 12 and the second valve 13 in all the gas injection wells 6, closing the third valve 18 in all the exhaust wells 7, and utilizing the magnetic force generated by electrifying the coil 2 to enable the working piston 3 to fall from the wellhead of the working well 8 to the step area 1 so as to compress the residual oxygen-containing gas and the seeped methane-containing gas in the working well 8;
f, the working piston 3 is repeatedly operated in the temperature-resistant and wear-resistant sleeve 4 by utilizing the magnetic force generated by electrifying the coil 2, so that the internal energy of methane gas in the working well 8 is improved, when the methane concentration is detected to reach a preset range by utilizing the methane concentration probe 15, the igniter 304 on the working piston 3 is controlled by the computer 11 to ignite and excite the methane-containing gas repeatedly compressed in the sieve tube 5 so as to generate combustion explosion, and the detonation gas and the combustion explosion shock wave generate radial cracks and annular cracks through holes in the sieve tube 5, so that the working well 8 is communicated with the gas injection well 6 and the gas exhaust well 7 through the radial cracks and the annular cracks;
g, the computer 11 receives height information which is measured by the height gauge 305 in the casing 4 and is sent by the working piston signal transceiver 306 through the working piston 3 by using the wellhead signal transceiver 10 in real time, and when the height of the working piston 3 is in a descending trend, the third valve 18 in the flexible pipe of the exhaust well 7 is opened to extract methane in the working well 8;
h after working piston 3 returns to step area 1, computer 11 control opens all gas injection well 6's first valve 12, utilizes methane concentration probe 15 and the oxygen concentration probe 16 that sets up in the gas injection well 6 real-time supervision after the explosion natural gas output change and methane concentration in the working well 8, guarantees that oxygen/methane concentration ratio is not more than 6: 1; when the yield of the natural gas is reduced and the methane concentration falls below 15%, the coil 2 is electrified to generate a magnetic field to push the working piston 3 to return to the wellhead, then the movable clamp 17 is used for fixing and then the power is cut off, and oxygen-containing clean gas is continuously introduced through the gas injection well 6 until the methane concentration approaches 5%;
i, repeating the steps e-h in the natural gas reservoir area, and arranging a plurality of groups of working wells 8 at intervals, so that the circular operation of burning explosion fracturing and methane gas extraction of the methane gas reservoir can be realized, and the permeability of the methane gas reservoir is greatly improved; the ignition timing of the plurality of groups of working wells 8 is controlled to create a time differential to produce a shaped pulse wave to maximize mechanical damage to the working wells 8.
The first embodiment,
Step 1, firstly, vertically drilling a working well 8 from a natural gas reservoir until the working well stops at a distance of 5-10 meters from the natural gas reservoir, then drilling in the working well by using drilling equipment with a small diameter to form a step area 1 in the working well, then directionally drilling a plurality of gas injection wells 6 and a plurality of exhaust wells 7 on two sides of the working well, cleaning residual broken stones of each well by using circulating pump pumping slurry, then cleaning and drying the working well by using oxygen-containing airflow, and building and reinforcing the orifice of the working well by using cement paste; 1/2, the diameter of the deep drilling hole at the position near the step area 1 is equal to that of the shallow drilling hole; the gas injection well 6 and the gas exhaust well 7 are arranged in parallel, the parallel distance between two groups of wells is 20-30 m, the interval between two adjacent wells in the same group is 10-15 m, and the working well 8 is arranged in the middle; the depth of the horizontal section of the gas injection well is larger than that of the horizontal section of the exhaust well, and the vertical distance between the horizontal sections of the gas injection well and the exhaust well is 20-40 m;
step 2, taking the step area 1 as a boundary, feeding a screen pipe 5 into an area below the step of the working well, arranging an annular rubber ring 9 matched with the step area at the step area, arranging a temperature-resistant and wear-resistant sleeve 4 with an outer wall tightly wound with the coil 2 in the area above the step, wherein the end part of the temperature-resistant and wear-resistant sleeve is in contact with the rubber ring, and the tail part of the temperature-resistant and wear-resistant sleeve extends out of a well mouth of the working well; wherein, the coil 2 is connected with a power supply and is controlled to be switched by a computer 11 arranged on the ground; the coil 2 is formed by combining a plurality of coil sections in parallel, and a single coil section is wound in a multilayer mode; the thickness of the sieve tube 5 is 10mm, and dense holes are drilled on the tube wall;
step 3, a working piston 3 is arranged in a temperature-resistant wear-resistant sleeve 4, a signal transceiver 10 is vertically arranged above a wellhead of a working well by utilizing a vertical frame, and the switch of the wellhead signal transceiver is controlled by a ground computer 11;
9, repeating the step 5 to the step 8 to realize the circular operation of the blasting and fracturing of the natural gas reservoir and the extraction of the natural gas, and greatly improving the permeability of the natural gas reservoir; the ignition time difference of each combustion and explosion working well 8 is controlled, so that energy-gathered pulse waves are generated to ensure that the mechanical damage to the working wells is maximized.
The methane in-situ combustion explosion damages surrounding rock mass and makes cracks, the product obtained after the oxygen and methane are mixed and combusted contains a large amount of carbon dioxide, the expansion detonation gas extrudes and expands the cracks and simultaneously enables the carbon dioxide to enter the cracks, the adsorption performance of the carbon dioxide is stronger than that of the methane, the methane in an adsorption state is displaced and desorbed in a large amount, the shale matrix releases the methane to enter the cracks around the horizontal well, the carbon dioxide is fixed in the shale matrix, the carbon emission of combustion explosion reaction products can be greatly reduced, and the extracted mixed gas can be used for production and life after being dried.
The working principle is as follows:
a gas injection well, an extraction well and a working well are vertically drilled in a natural gas reservoir, oxygen is transferred from the gas injection well to the working well through an artificial fracture, a methane explosion reaction is excited through an igniter 304, methane is extracted through an artificial fracture net, the volume of a working piston 3 is compressed through self weight, the volume of the working piston is expanded through detonation gas, and circular explosion fracturing is achieved. The shale is fractured by in-situ combustion and explosion of methane, and the working principle of a fracturing system for fracturing a rock mass comprises the following steps:
after methane in-situ combustion explosion, smashing rock mass around a horizontal well at ultrahigh pressure, wherein shock waves cause tangential tensile stress in the rock at a speed of 3000-5000 m/s, so that radial cracks are generated and develop towards a free surface direction, the shock waves need 1-2 ms when expanding to the radial cracks from the horizontal well to the surrounding rock mass, centripetal tensile stress opposite to the action direction of compression stress waves is generated, shale particles generate reverse radial motion, and annular cracks are formed;
the pressure before the shock wave reaches the free surface is a positive value, when the shock wave reaches the free surface and is reflected, the pressure of the wave is changed into a negative value, namely, the compression stress wave is changed into the tensile stress wave, and the shale is broken under the action of the reflected tensile stress, wherein the pressure is 10-20 ms after the blast;
thirdly, the radial initial crack of the shale is rapidly expanded under the dual actions of tensile stress and air wedge under the influence of the ultrahigh pressure of the combustion and explosion gas.
This application uses magnetic force to promote the piston that mechanical structure was compared to the working piston: magnetic force promotes piston simple structure, and magnetic force promotes and can make the piston reciprocate in order to compress work repeatedly, and mechanical connecting rod drives piston structure and contains a plurality of rigid member, just can normally work through suitable matching combination before the compression work. The piston is pushed by magnetic force to have larger compression and expansion strokes, the mechanical connecting rod drives the piston structure to be limited by the physical size of the rigid component, so that the gas cannot be fully compressed, the work energy of the blasting work in the direction of the wellhead can be released, and the possibility that the connecting rod mechanism is damaged by the work of the blasting gas exists. The piston pushed by magnetic force can be repeatedly used, and is suitable for working wells with standard diameters drilled in batches, and the connecting rod mechanism cannot be repeatedly used due to the fact that the connecting rod mechanism needs to be matched with the depth of the working wells.
Claims (10)
1. The utility model provides a circulating natural gas of methane normal position blasting fracturing intensification is taken out and is adopted system which characterized in that: the well drilling device comprises a working well (8) which is drilled into a natural gas reservoir, wherein the working well (8) is a stepped well with a thick upper end and a thin lower end, a well section with a thick upper end is a piston well section, and a fracturing well section is washed at the lower end; wherein the joint of the piston well section and the fracturing well section is a step (1), a rubber ring (9) for sealing is arranged on the step (1), a sieve tube (5) is arranged in the fracturing well section below the rubber ring (9), a plurality of round holes are distributed on the sieve tube (5), a temperature-resistant and wear-resistant sleeve (4) with the tail part extending out of a well mouth of a working well (8) is arranged in the piston well section, a coil (2) is tightly wound on the outer side of the temperature-resistant and wear-resistant sleeve (4), the coil (2) is connected with a power supply, a working piston (3) with matched size is arranged in the temperature-resistant and wear-resistant sleeve (4), a well mouth signal transceiver (13) is vertically arranged above the pipe mouth of the temperature-resistant and wear-resistant sleeve (4) through a support, a movable clamp (17) for fixing the working piston (3) is arranged in the top of the temperature-resistant and wear-resistant sleeve (4), a plurality of gas injection wells (6) and a plurality of exhaust wells (7) are respectively arranged at equal intervals on two sides of the working well (8), wherein the gas injection well (6) is connected with the side wall at the bottom of the fracturing well section through the horizontal well section, and the gas exhaust well (7) is connected with the side wall above the fracturing well section through the horizontal well section; working piston (3) include through two parts about the bolt is articulated, and upper portion includes permanent magnet (301), and permanent magnet (301) outside parcel has temperature resistant wear-resisting shell (302), and the lower part is the counterweight, and upper portion top and lower part bottom are equipped with polyurea coating (303) respectively, and wherein polyurea coating (303) the round play that lower part bottom set up is equipped with some firearm (304), and the upper portion top is equipped with altimeter (305) and working piston signal transceiver (306) respectively.
2. The methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system according to claim 1, which is characterized in that: a plurality of gas injection wells (6) and a plurality of exhaust wells (7) are arranged oppositely on two sides of a working well (8) at equal intervals, the gas injection wells (6) and the exhaust wells (7) are arranged in parallel, two groups of wells are arranged in parallel at intervals of 20-30 m, two adjacent wells in the same group are arranged at intervals of 10-15 m, and the working well (8) is arranged in the middle.
3. The methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system according to claim 1, which is characterized in that: the horizontal well section of the gas injection well (6) and the gas exhaust well (7) respectively comprises a first valve (12) and a second valve (13), wherein the first valve (12) is arranged at the position, close to the sieve tube (5), of the horizontal well section, the second valve (13) is provided with a dustproof filter screen (14), and a methane concentration probe (15) and an oxygen concentration probe (16) are fixed in the horizontal well section by utilizing the second valve (13); and a third valve (18) is arranged in the end part of the horizontal well section of the exhaust well (7) close to the sieve tube (5).
4. An extraction method of the methane in-situ combustion-explosion fracturing circulating type natural gas enhanced extraction system of claim 1 is characterized by comprising the following steps:
a, vertically drilling a working well (8) from a natural gas reservoir, forming a step (1) at a position 5-10 meters away from the natural gas reservoir from the working well (8) through a diameter difference, dividing the working well (8) into an upper piston well section and a lower fracturing well section, then directionally drilling a plurality of gas injection wells (6) and a plurality of exhaust wells (7) from the earth surface on two sides of the working well (8), and cleaning the gas injection wells (6) and the exhaust wells (7) by using oxygen-containing gas flow;
b, feeding a screen pipe (5) into a fracturing well of a working well (8), then placing a rubber ring (9) in the step area (1), installing a temperature-resistant and wear-resistant sleeve (4) wound with a coil (2) above the rubber ring (9), and connecting the coil (2) into a power supply;
c, a working piston (3) is arranged in the temperature-resistant wear-resistant sleeve (4), and a signal transceiver (10) is vertically arranged above a wellhead of a working well (8) by utilizing a vertical frame;
d, placing a flexible steel pipe provided with a first valve (12), a second valve (13), a dustproof filter screen (14), a methane concentration probe (15) and an oxygen concentration probe (16) into the gas injection well (6), and placing a flexible steel pipe provided with a third valve (18) into the exhaust well (7);
e, closing the first valves (12) and the second valves (13) in all the gas injection wells (6), closing the third valves (18) in all the gas exhaust wells (7), and enabling the working piston (3) to fall to the step area (1) from the well mouth of the working well (8) by utilizing the magnetic force generated by electrifying the coil (2) so as to compress the residual oxygen-containing gas and the seeped methane-containing gas in the working well (8);
f, enabling the working piston (3) to repeatedly work in the temperature-resistant and wear-resistant sleeve (4) by utilizing the magnetic force generated by electrifying the coil (2), so that the internal energy of methane gas in the working well (8) is improved, when the methane concentration is detected to reach a preset range by utilizing the methane concentration probe (15), utilizing the computer (11) to control an igniter (304) on the working piston (3) to ignite and excite the methane-containing gas repeatedly compressed in the sieve tube (5) to generate blasting, and enabling the blasting gas and blasting shock waves to generate radial cracks and annular cracks through holes in the sieve tube (5), so that the working well (8) is communicated with the gas injection well (6) and the gas exhaust well (7) through the radial cracks and the annular cracks;
g, the computer (11) receives height information which is measured by the working piston (3) in the casing (4) through the height meter (305) in real time through the wellhead signal transceiver (10), and is sent through the working piston signal transceiver (306), and when the height of the working piston (3) is in a descending trend, a third valve (18) in a flexible pipe of the exhaust well (7) is opened to extract methane in the working well (8);
h work piston (3) return to step region (1) after, first valve (12) of all gas injection wells (6) are opened in computer (11) control, utilize methane concentration probe (15) and oxygen concentration probe (16) that set up in gas injection well (6) real-time supervision after the explosion natural gas output change and methane concentration in work well (8), guarantee that oxygen/methane concentration ratio is not more than 6: 1; when the yield of the natural gas is reduced and the methane concentration falls below 15%, the coil (2) is electrified to generate a magnetic field to push the working piston (3) to return to a wellhead, then the working piston is fixed by a movable clamp (17), then the power is cut off, and oxygen-containing clean gas is continuously introduced through the gas injection well (6) until the methane concentration approaches 5% and then the operation is stopped;
i, multiple groups of working wells (8) are arranged in the natural gas reservoir area at intervals in the steps e-h, so that the circular operation of explosion and fracturing of the methane gas reservoir and methane gas extraction can be realized, and the permeability of the methane gas reservoir is greatly improved; the ignition time of a plurality of groups of working wells (8) is controlled to form a time difference, so that energy-gathered pulse waves are generated to maximize the mechanical damage to the working wells (8).
5. The extraction method according to claim 4, characterized in that: after drilling, the working well (8), the gas injection well (6) and the exhaust well (7) need to be pumped with circulating pump slurry to clean residual broken stones in each well, then the working well (8), the gas injection well (6) and the exhaust well (7) are cleaned and dried by using oxygen-containing airflow, and a drilling orifice is built and reinforced by using cement slurry.
6. The extraction method according to claim 4, characterized in that: the coil (2) is formed by combining a plurality of coil sections in parallel, and a single coil section is wound in a multilayer mode.
7. The extraction method according to claim 4, characterized in that: the diameter of the fracturing well section drilling hole of the step (1) is 1/2 of the diameter of the piston well section.
8. The extraction method according to claim 4, characterized in that: the pumping pressure of the gas injection well (6) is controlled to be 5-10 MPa, and the oxygen-containing concentration of pumped gas is 10%; the preset methane concentration of the blasting is 5-15%.
9. The extraction method according to claim 4, characterized in that: the thickness of the sieve tube (5) is 10mm, and dense holes are drilled on the tube wall.
10. The extraction method according to claim 4, characterized in that: the depth of the horizontal section of the gas injection well (6) should be larger than that of the horizontal section of the exhaust well (7), and the vertical distance of the horizontal section should be 20-40 m.
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